Is ${} supported?

Is ${} supported?

[Anthony Heading]

The "null" parameter seems useful to allow the following sort of thing:

% echo ${(j/+/):-{one,two,three}}
one+two+three

But does it only work by accident, or can it be relied on?  Should
it be documented?

Anthony

Re: Is ${} supported?

[Zoltan Hidvegi]

> The "null" parameter seems useful to allow the following sort of thing:
> 
> % echo ${(j/+/):-{one,two,three}}
> one+two+three
> 
> But does it only work by accident, or can it be relied on?  Should
> it be documented?

It can be relied on.  I suspect that I have several scripts relying on
that.  It should be documented of course.

Zoltan

Re: Is ${} supported?

[Peter Stephenson]

Zoltan Hidvegi wrote:
> > The "null" parameter seems useful to allow the following sort of thing:
> > 
> > % echo ${(j/+/):-{one,two,three}}
> > one+two+three
> 
> It can be relied on.

Just as a matter of interest, why does the following not work the same
way?

% print ${(j/,/):-/proc/*(U:t)} 
23020 23048 23051 23052 23062 26604

-- 
Peter Stephenson <pws@ifh.de>       Tel: +49 33762 77366
WWW:  http://www.ifh.de/~pws/       Fax: +49 33762 77413
Deutches Electronen-Synchrotron --- Institut fuer Hochenergiephysik Zeuthen
DESY-IfH, 15735 Zeuthen, Germany.

Re: Is ${} supported?

[Zoltan Hidvegi]

Peter Stephenson wrote:
> Just as a matter of interest, why does the following not work the same
> way?
> 
> % print ${(j/,/):-/proc/*(U:t)} 
> 23020 23048 23051 23052 23062 26604

Because globbing performed much later than expansion.  The order is
precisely described in zshexpn.man.

Zoltan